VHDL 矩阵键盘输入 - 获取六位数字并保存

以下是一个 VHDL 代码示例，用于从 6 个数字键获取输入并将其保存在一个 6 位二进制寄存器中：

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity keypad_input is
  port(
    clock     : in std_logic;
    reset     : in std_logic;
    row       : in std_logic_vector(3 downto 0);
    col       : out std_logic_vector(3 downto 0);
    digit_out : out std_logic_vector(5 downto 0)
  );
end entity keypad_input;

architecture behavioral of keypad_input is

  signal row_val : std_logic_vector(3 downto 0);
  signal col_val : std_logic_vector(3 downto 0);

  type state_type is (IDLE, WAIT1, WAIT2, WAIT3, WAIT4, WAIT5, WAIT6);
  signal state : state_type := IDLE;

  signal digit_reg : std_logic_vector(5 downto 0);

begin

  -- Column signals are active-low, so invert them
  col <= not col_val;

  -- Register to hold the six-digit input
  process(clock)
  begin
    if rising_edge(clock) then
      if reset = '1' then
        digit_reg <= (others => '0');
      else
        digit_reg <= digit_reg(digit_reg'high-1 downto 0) & row_val(0);
      end if;
    end if;
  end process;

  -- State machine to handle keypad input
  process(clock)
  begin
    if rising_edge(clock) then
      case state is
        when IDLE =>
          if row_val(0) = '1' then
            state <= WAIT1;
          end if;
        when WAIT1 =>
          if row_val(0) = '0' then
            state <= WAIT2;
          end if;
        when WAIT2 =>
          if row_val(0) = '1' then
            state <= WAIT3;
          end if;
        when WAIT3 =>
          if row_val(0) = '0' then
            state <= WAIT4;
          end if;
        when WAIT4 =>
          if row_val(0) = '1' then
            state <= WAIT5;
          end if;
        when WAIT5 =>
          if row_val(0) = '0' then
            state <= WAIT6;
          end if;
        when WAIT6 =>
          if row_val(0) = '1' then
            state <= IDLE;
            digit_out <= digit_reg;
          end if;
      end case;
    end if;
  end process;

  -- Debounce logic for row signals
  process(clock)
  begin
    if rising_edge(clock) then
      row_val <= row_val(2 downto 0) & row(3);
    end if;
  end process;

  -- Assign column signals to constant values
  col_val <= "1110";

end architecture behavioral;

该代码采用一个状态机来处理按键输入，并使用一个 6 位二进制寄存器来保存数字。每当用户按下一个数字键时，该数字将被添加到寄存器的末尾。当用户按下第六个数字键时，当前寄存器的值将被输出到 digit_out 端口，表示用户输入的完整数字。

为了避免按键反弹问题，该代码使用一个简单的行信号去抖逻辑。在行信号发生变化时，将其最新的值与前面的三个值连接在一起，以确保每个变化都被稳定地捕获和处理。